Running cost comes down to wattage, hours and your rate. In Idaho the rate is 12.35 cents per kWh, which is 33.0 percent below the national average. Here is what that means for a space heater.
A space heater drawing 1,500 W costs $0.19 per hour in Idaho. Run 6 hours a day that is $1.11 daily, $33.35 a month and $406 a year, which is $200 less than the same appliance at the US average rate.
Space heater cost at Idaho rates
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Planning estimate. The rate box is prefilled with a regional average; the figure on your own bill is the one that matters. Power is draw while running, not while switched on.
Cost by hours used per day in Idaho
| Hours/day | Energy | Per day | Per month |
|---|---|---|---|
| 1 h | 1.50 kWh | $0.19 | $5.56 |
| 2 h | 3.00 kWh | $0.37 | $11.12 |
| 4 h | 6.00 kWh | $0.74 | $22.23 |
| 6 h | 9.00 kWh | $1.11 | $33.35 |
| 8 h | 12.00 kWh | $1.48 | $44.46 |
| 12 h | 18.00 kWh | $2.22 | $66.69 |
| 24 h | 36.00 kWh | $4.45 | $133 |
Cost by wattage at 12.35 cents
| Rated power | Per hour | Per day | Per month |
|---|---|---|---|
| 500 W | $0.06 | $0.37 | $11.12 |
| 750 W | $0.09 | $0.56 | $16.67 |
| 1,000 W | $0.12 | $0.74 | $22.23 |
| 1,200 W | $0.15 | $0.89 | $26.68 |
| 1,500 W | $0.19 | $1.11 | $33.35 |
Find the row matching the nameplate on your own unit. Within a single appliance category the spread is often wider than the difference between categories, so the label is worth reading.
Heating season in Idaho
Idaho carries a real but moderate heating season, commonly four to five months. That is long enough for equipment efficiency to matter and short enough that payback on an upgrade takes longer than it would further north.
Why Idaho pays what it does
Idaho is a regulated market, so your utility is the only supplier and the rate is set through the state commission rather than by competition. Pricing tends to be steadier than in deregulated states, and there is no switching decision available. The levers are all on your side of the meter.
At 12.35 cents, Idaho ranks 1 of 51 from cheapest to most expensive. The West regional average is 19.65 cents. Roughly half of any residential bill is transmission and distribution rather than generation, which is why rates keep climbing even when fuel prices fall.
How this compares across the country
The same space heater on the same schedule, in the cheapest and dearest states:
| State | Rate | Per month | Per year |
|---|---|---|---|
| Idaho | 12.35¢ | $33.35 | $406 |
| Utah | 12.96¢ | $34.99 | $426 |
| Idaho | 12.35¢ | $33.35 | $406 |
| California | 33.25¢ | $89.78 | $1,092 |
| Hawaii | 52.00¢ | $140 | $1,708 |
Lowering the number in Idaho
- Use the low setting when it holds temperature. 750 W instead of 1,500 W halves the running cost.
- Put it on a timer or smart plug. The biggest waste is a heater running in an empty room.
- Turn the central thermostat down at the same time. Adding a space heater without lowering the house setpoint adds cost and removes nothing.
- Close the door and block the draft under it. Zone heating only saves money if the zone is sealed.
- One heater per circuit, plugged into the wall. A 1,500 W heater draws 12.5 amps, which is already at the continuous limit for a 15 A circuit.
Offsetting it with solar in Idaho
This load uses about 9.00 kWh a day. Covering that would take roughly 7 standard 400 W panels at typical sun hours, an array of about 2.80 kW. Because it offsets electricity worth 12.35 cents rather than the national 18.44 cents, the same array is worth less here than the national payback figures suggest.
Resistance heating is the worst possible solar load. It draws full rated power the whole time it runs and there is no efficiency to gain, so the panel count is driven purely by hours of use. Full sizing, including battery and inverter requirements, is on the solar sizing page for this appliance.